U.S. patent number 4,096,315 [Application Number 05/750,655] was granted by the patent office on 1978-06-20 for process for producing a well-adhered durable optical coating on an optical plastic substrate.
This patent grant is currently assigned to The United States of America as represented by the Administrator of the. Invention is credited to Ronald M. Kubacki.
United States Patent |
4,096,315 |
Kubacki |
June 20, 1978 |
Process for producing a well-adhered durable optical coating on an
optical plastic substrate
Abstract
A process for coating an optical plastic substrate, for example
polymethylmethacrylate (PPMA), with a single layer coating for the
purpose of improving the durability of the plastic, the coating
being deposited by a low temperature plasma polymerization
process.
Inventors: |
Kubacki; Ronald M. (Cupertino,
CA) |
Assignee: |
The United States of America as
represented by the Administrator of the (Washington,
DC)
|
Family
ID: |
25018721 |
Appl.
No.: |
05/750,655 |
Filed: |
December 15, 1976 |
Current U.S.
Class: |
428/412; 427/164;
427/302; 427/322; 427/387; 427/491; 427/536; 428/447; 522/141;
522/148; 522/172; 351/159.57 |
Current CPC
Class: |
B29D
11/00865 (20130101); G02B 1/105 (20130101); G02B
1/14 (20150115); Y10T 428/31663 (20150401); Y10T
428/31507 (20150401) |
Current International
Class: |
B29D
11/00 (20060101); G02B 1/10 (20060101); B32B
027/36 () |
Field of
Search: |
;427/34,38,41,162,164,299,302,375,387,44 ;428/412,447 ;351/166 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Smith; Ronald H.
Assistant Examiner: Konopacki; Dennis C.
Attorney, Agent or Firm: Brekke; Darrell G. Kempf; Robert F.
Kinberg; Robert
Government Interests
The invention described herein was made in the performance of work
under a NASA contract and is subject to the provisions of Section
305(a) of the National Aeronautics and Space Act of 1958, Public
Law 85-568 (72 Stat. 435; 42 U.S.C. 2457(a)).
Claims
What is claimed is:
1. A method of coating an optical plastic substrate with an
abrasion resistant coating comprising the sequential steps of:
a. exposing the substrate in an evacuated plasma polymerization
reactor chamber to a first plasma that forms hydroxyl groups on
said substrate surface,
b. evacuating the reactor chamber,
c. exposing the substrate in the reactor chamber to a second
plasma, said second plasma being a polymerizable monomer to produce
a coating of the monomer on the substrate, the coating being less
than 3000 nm thick and wherein the monomer contains silicon,
d. evacuating the reaction chamber,
e. exposing the substrate to a third plasma for a predetermined
time at a predetermined pressure, said third plasma being selected
from the group consisting of noble gases, oxygen, nitrogen, and
air, and
f. removing the substrate from the reactor chamber.
2. The method of coating an optical plastic substrate as recited in
claim 1 wherein said first plasma is selected from the group
consisting of oxygen, hydrogen, air and water vapor.
3. The method of coating an optical plastic substrate as recited in
claim 1 wherein said third plasma is employed to cross-link and
stress-relieve the silicon monomer and is selected from the group
consisting of a noble gas, oxygen and nitrogen.
4. The method of coating an optical plastic substrate as recited in
claim 1 wherein said first plasma is water vapor and said third
plasma is argon.
5. A method of coating an optical plastic substrate as recited in
claim 1 wherein said monomer is selected from the group consisting
of vinyltrimethylsilane, vinyltrimethylethoxysilane,
vinyldimethylethoxysilane, hexamethyldisilizane, and mixtures
thereof.
6. The method of coating an optical plastic substrate as recited in
claim 1 wherein exposure of the substrate to the first plasma is
undertaken at a pressure of about 15 to 25 nt/m.sup.2 within the
reactor chamber.
7. The method of coating an optical plastic substrate as recited in
claim 5 wherein the step of producing the monomer coating is
undertaken at a flow rate of 1 to 5 cc/min. at standard temperature
and pressure, with an interior pressure within the reactor chamber
in the range of 6.67 to 13.33 nt/m.sup.2 and at an RF power of 20
to 60 watts RMS with an RMS current in the range of 1.24 to 2.07
amps.
8. The coating of an optical plastic substrate as recited in claim
7 wherein the step of producing the monomer coating on the
substrate is undertaken at a deposition rate in the range of 0.1 to
0.25 nm/sec.
9. A method of coating an optical plastic substrate as recited in
claim 5 wherein the step of exposing the substrate to the third
plasma is undertaken at a pressure of 20 nt/m.sup.2 at 100 watts of
RF power for 200 to 1,000 seconds.
10. A method of coating an optical plastic substrate as recited in
claim 9 wherein the third plasma is argon.
11. A method of coating an optical plastic substrate as recited in
claim 5 wherein the monomer is a mixture of approximately 50%
hexamethyldisilizane and 50% vinyl dimethylethoxysilane by
volume.
12. The method of coating an optical plastic substrate as recited
in claim 5 wherein the monomer is a mixture of approximately 50%
vinyltrimethylsilane and 50% hexamethyldisilizane by volume.
13. The method of coating an optical plastic substrate as recited
in claim 5 wherein the monomer is a mixture of approximately 50%
vinyltrimethylethoxysilane and 50% hexamethyldisilizane.
14. The method of coating an optical plastic substrate as recited
in claim 1 further comprising the step of cleaning the substrate
prior to the step of exposing the substrate in the reactor chamber
to the first plasma by dipping the substrate in a first solvent to
remove water soluble contaminants and then rinsing the substrate in
a second solvent to remove the first solvent and finally vapor
degreasing the substrate and allowing the substrate to dry before
insertion into the plasma reactor.
15. The method of coating an optical plastic substrate as recited
in claim 1 wherein said substrate is polymethylmethacrylate.
16. The method of coating an optical plastic substrate as recited
in claim 1 wherein said substrate is a polycarbonate.
17. The method of coating an optical plastic substrate as recited
in claim 1 wherein said substrate is a polystyrene.
18. The method of coating an optical plastic substrate as recited
in claim 1 wherein said substrate is a
polystyrenepolymethylmethacrylate copolymer.
19. A method of coating an optical plastic substrate as recited in
claim 1 wherein the optical plastic substrate has a higher
refractive index than the refractive index of the monomer coating
and the monomer cOating is deposited to have an optical thickness
equal to an odd multiple of 1/4 of the wavelength of the midpoint
of the light range over which the substrate is to be utilized.
20. A coated optical plastic substrate produced according to the
method of claim 1.
21. An optical plastic substrate having an abrasion resistant
coating comprising:
a. an optical plastic substrate selected from the group consisting
of polymethylmethacrylate, a polycarbonate, a polystyrene, and a
polystyrene-polymethylmethacrylate copolymer,
b. an interlayer hydroxyl group coating on at least one surface of
the substrate, and
c. an outer, plasma polymerized monomer coating over the hydroxyl
interlayer, the monomer being selected from the group consisting of
vinyltrimethylsilane, vinyltrimethylethoxysilane,
vinyldimethylethoxysilane, hexamethyldisilizane and mixtures
thereof.
22. A coated optical plastic substrate as recited in claim 21
wherein the combined interlayer and monomer coating is chosen to
have a lower refractive index than the refractive index of the
optical plastic substrate and has an optical thickness equal to an
odd multiple of 1/4 of the wavelength of the midpoint of the light
range over which the substrate is to be utilized.
Description
BACKGROUND OF THE INVENTION
The invention relates to abrasion resistant coatings and methods
for their application, and more particularly to a well-adhered
abrasion resistant coating for plastics.
Traditionally, glass lenses have been used in cameras, projectors,
telescopes and other optical instruments. Recent developments have
shown that lenses can be prepared from thermal plastics by
injection molding. The primary advantages of producing lenses by
injection molding are that the lenses have a low material cost, are
light weight and only require the use of unskilled labor to be
produced since the lenses are in a finished state when released
from the mold. Such injection molded lenses are highly resistant to
shattering and do not require any subsequent milling, grinding or
polishing after the molding step. Such lenses are, however, not
durable, and tend to scratch easily under routine cleaning.
One way of protecting the plastic lenses is to coat them with an
abrasion resistant material. The problem has been to find a
suitable material which is both abrasion resistant and yet durable
and well-adhered to the plastic. Many suitable coatings such as the
type of coatings which are put on glass to act as anti-reflection
coatings are difficult to put onto an injection molded plastic lens
because of the requirements of the coating process. For example,
glass lenses are typically coated with a single layer
anti-reflection coating of magnesium fluoride (MgF.sub.2).
Magnesium fluoride is deposited on the glass lens by vapor
deposition, that is, by vaporizing magnesium fluoride in a vacuum
chamber and then allowing the vapor to contact the heated lens. The
lens must be heated to approximately 300.degree. C. This elevated
substrate temperature is required to improve adhesion and
durability of the magnesium fluoride coating to the glass
surface.
Depositing magnesium fluoride on plastic lenses by vapor deposition
is unsatisfactory because thermal plastics generally cannot
withstand the high temperatures required for satisfactory adhesion
and durability of the magnesium fluoride coating. Also, such
coatings tend to show restricted performance during environmental
testing due to poor adhesion.
If a soft magnesium fluoride coating is deposited on glass, then
the standard procedure requires baking of the coated glass element
at a temperature between 300.degree. C. and 500.degree. C. Plastics
suitable for optical use are not able to maintain dimensional
stability and often oxidize at these temperatures and would be
destroyed by the baking process.
Other coating processes on plastic for increased durability of the
surface have been attempted by dipping the substrate into a
solution of the coating material and then removing the substrate.
See, for example, U.S. Pat. No. 3,953,115. The problem with coating
in this manner is that there is virtually no control over the film
thickness. The films do not shown improved durability at
thicknesses less than 1 micron and are too thick and non-uniform to
be of use as an optical coating on the involved geometry of a lens.
It is known to apply similar coatings to glass by plasma
polymerization employed as a light guide, see for example, U.S.
Pat. No. 3,822,928, but the problem of obtaining a well-adhered
coating on an optical plastic substrate has remained until now.
SUMMARY OF THE INVENTION
The above and other disadvantages of prior art methods of providing
an anti-abrasion coating for a plastic lens are overcome by the
present invention of a method comprising the steps of exposing the
substrate in an evacuated plasma polymerization reactor chamber to
a first plasma that forms hydroxyl groups on the lens surface,
evacuating the reactor chamber, exposing the substrate in the
reactor chamber to a second or monomer plasma for a predetermined
time and at a predetermined pressure to produce a coating of the
monomer on the substrate to a thickness that is less than 3000 nm,
100 nm .+-. 20 nm being most preferred, evacuating the reactor
chamber, and exposing the substrate to third plasma for a
predetermined time at a predetermined pressure. The substrate is
finally removed from the reactor chamber. In the preferred
embodiment of the invention, the first, hydroxyl group forming
plasma is selected from hydrogen, oxygen, air and water vapor,
water vapor being most preferred. The second or monomer plasma is a
silicon containing monomer and is preferably selected from at least
one of the group consisting of vinyltrimethylsilane,
vinyltrimethylethoxysilane, vinyldimethylethoxysilane, and
hexamethyldisilizane. The monomers can be mixtures of these
components, the preferred mixture being a 50-50 mixture (by volume)
of vinyldimethylethoxysilane and hexamethyldisilizane. The third
plasma is selected from one of the noble gases, oxygen, nitrogen
and air, argon being the most preferred.
During the step of exposing the substrate to the first plasma, the
pressure within the reactor chamber is maintained at approximately
15-25 nt/m.sup.2. If H.sub.2 O plasma is employed, it can be
produced by ionizing H.sub.2 O vapor within the reactor chamber by
generating an RF current, for example, at 60 watts of power by
13.56 mHz for 300 seconds.
One important step of the above-described method is the preliminary
step of subjecting the substrate to the hydroxyl group forming
plasma vapor. It is believed that it is this step which allows for
the good adherence qualities of the coating. Previously known
methods of applying such coatings to such substrates, such as
glass, for example, did not involve this step. See, for example
U.S. Pat. No. 3,822,928. It should be noted that the purpose in
providing the coating in the aforementioned patent was not to
provide an abrasion resistant coating, but simply to provide a thin
film light guide coating on a glass substrate.
A second important step in the above-described method is the step
of subjecting the coated substrate to a third plasma after the
monomer is deposited. The third plasma, preferably argon plasma, is
at a pressure of 10-30 nt/m.sup.2 at 30-300 watts of RF power. The
bombardment is undertaken for a time period ranging from 200 to
1,000 seconds. The theory behind this treatment by, for example,
argon plasma, is to cross-link and stress-relieve the polymer films
by ultraviolet radiation, temperature elevation, and electron
bombardment. As stated previously, in other less preferred
embodiments of the present method, oxygen, air, nitrogen, and other
noble gases may be used for the plasma generation.
It is, therefore, an object of the present invention to provide a
well-adhered durable, optical coating for an optical plastic
substrate by the process of plasma polymerization.
It is another object of the invention to provide an injection
molded optical plastic lens having a well-adhered anti-abrasion
coating.
It is still a further object of the invention to provide a low
temperature method for depositing an anti-abrasion coating on an
optical plastic substrate.
It is yet another object of the invention to provide a low cost
method of applying an anti-abrasion coating to a plastic lens.
It is a further object of the invention to provide a method of
depositing an anti-abrasion coating to a plastic lens, irrespective
of the lens curvature.
The foregoing and other objectives, features and advantages of the
invention will be more readily understood upon consideration of the
following detailed description of certain preferred embodiments of
the invention, taken in conjunction with the accompanying
drawing.
BRIEF DESCRIPTION OF THE DRAWING
The FIGURE is a diagrammatic illustration of a plasma
polymerization reactor.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring now more particularly to FIG. 1, a typical plasma
polymerization coating reactor 10 is illustrated as having an
enclosed chamber 12, a "hot" electrode 14, ground electrode 16
spaced from the hot electrode 14, and a substrate holder 18
positioned between the electrodes 14 and 16. The monomer to be
deposited on the substrate is fed in through an inlet pipe 20 which
exits through a hole in the hot electrode 14. An exit 22 is
provided in the chamber 12 and is connected to a trap and a vacuum
pump 23. The electrode 16 is connected to the circuit ground and a
current probe (not shown). The interior of the chamber 12 is
monitored by a pressure gauge 24. The hot electrode 14 is connected
to an adjustable RF power supply 26. A substrate 28, for example, a
plastic lens to be coated, is fixtured midway between the
electrodes 14 and 16 which are spaced approximately 2 inches apart.
Positioning the substrate between the electrodes, as opposed to
resting it on the lower electrode 16, permits both sides of the
substrate 28 to be coated simultaneously. The lens holder 18 is
electrically isolated from the lower electrode 16 by legs or other
means of support made of an electrically insulating material, such
as polytetrafluoroethylene, known under the trademark Teflon. The
chamber 12 may be a glass bell jar placed over the electrode
assembly. The chamber 12 is evacuated to a background pressure of
less than 0.67 nt/m.sup.2 to remove any reactants available in the
room atmosphere.
Prior to its insertion into the chamber, the optical plastic
substrate 28 is cleaned to remove contaminants and to improve
adhesion of the coating. As an illustration of such a cleaning
step, the substrate can be dipped into a first solvent, such as
DuPont Freon.RTM. solvent TWD 602 to remove water soluble
contaminants. The substrate can then be rinsed in a second solvent
such as DuPont Freon.RTM. TF to remove the first solvent. The
substrate can then be vapor degreased in DuPont Freon.RTM. TF vapor
and allowed to dry before insertion into the reactor.
The polymerization process for coating the substrate 28 is then
begun by the following steps. After the initial evacuation, a
vessel (not shown) containing the hydroxyl group forming plasma,
for example distilled H.sub.2 O, is exposed to the inlet 20 of the
reactor 10. A throttling valve 30 is located between the reactor
and the vacuum pump 23 to limit the pumping rate. A flow valve 32
is positioned in the inlet line 20 to control the input flow. The
throttling valve 30 and the flow valve 32 are adjusted to yield
15-25 nt/m.sup.2 of pressure within the reactor.
The hydroxyl group forming vapor is then ionized by the RF
generator into plasma. High frequency voltage is applied across the
electrodes by means of the RF supply with its associated impedance
matching network 26 to initiate and sustain the plasma. The plasma
is very uniform as evidenced by the uniform glow and is confined to
an area primarily between the two electrodes 14 and 16. The power
output is approximately 30-300 watts and is used for approximately
a 100-1000 second duration. Hydroxyl groups (OH--) are thus
deposited or grated as a tenacious intermediate layer which results
in improved adhesion of a later-deposited protective layer to the
plastic substrate. This was borne out by the applicant's
experiments which showed that films deposited without the
pretreatment of hydroxyl group forming plasma bombardment on
optical plastic substrates would not pass the standard military
specification adhesion test for optics as spelled out in
MIL-C-675A. This test involves the placing of adhesive tape on the
film and removing it to examine the film adherence. Films deposited
on PMMA (polymethylmethacrylate) without the pretreatment failed
the test, whereas those deposited in conjunction with the
pretreatment of, for example, H.sub.2 O vapor plasma, repeatedly
passed the test.
Following the hydroxyl group forming first plasma bombardment step,
the chamber 12 is evacuated and pumped to less than 0.67 nt/m.sup.2
of pressure. Once this evacuation has been completed, a vessel (not
shown) of the monomer to be coated by plasma polymerization on the
substrate is exposed to the inlet pipe 20 of the reactor 10. Once
again, flow is restricted by the flow valve 32 and evacuation is
limited by the throttling valve 30. The monomer is then coated on
the substrate by plasma polymerization under conditions more fully
described hereinafter. Suitable monomers have been found to include
vinyltrimethylsilane, vinyltrimethylethoxysilane,
vinyldimethylethoxysilane, hexamethyldisilizane, as well as several
mixes of silanes. All ratios for mixtures were by volume and are
not to be considered absolute ratios. The following mixtures were
found to be successful: 50% hexamethyldisilizane/50%
vinyltrimethylethoxysilane; 50% vinyltrimethylsilane/50%
hexamethyldisilizane; and 50% vinyldimethylethoxysilane/50%
hexamethyldisilizane. The most successful of all of the above
mixtures proved to be a mixture of 50%
vinyldimethylethoxysilane/50% hexamethyldisilizane.
The conditions for deposition were approximately as follows: flow
rate of 1 to 5 cc/min. at STP (air). Pressure was in the range of
6.67 to 13.33 nt/m.sup.2. The RF power of the reactor was 20 to 60
watts RMS with an RMS current in the range of 1.24 to 2.07
amps.
Deposition rates were in the range of 0.1 to 0.25 nm/sec. of
thickness of the coating. It was found that the films coated onto
the substrate must be less than 3000 nm in thickness as at that
point the internal film stresses are high enough to allow
delamination of the film from the substrate. The average index of
refraction of these films is 1.50. When the film was deposited on
PMMA, with an index of 1.49, no anti-reflection behavior is
exhibited due to the matching indices of refraction. However, if
the substrate is chosen to be an optical plastic other than PMMA
and having a higher refractive index then by monitoring the
thickness of the coating to be an odd multiple of 1/4 of the
expected mid-wavelength to which the optical substrate will be
subjected, then the coating will also serve as an anti-reflection
coating. Such substrates could be a polystyrene, or a polycarbonate
such as is marketed under the trademark LEXAN.RTM. by General
Electric and DYLARK.RTM. by Arco. DYLARK.RTM. is a polystyrene-PMMA
co-polymer.
The duration of the deposition is monitored and is used to control
film thickness. The plasma is extinguished at the end of a
predetermined deposition time by turning off the RF power to the
electrodes 14 and 16. After the deposition of the coating has been
thus terminated, the system is again evacuated to less than 0.67
nt/m.sup.2. A third gas such as argon is then flowed into the
reactor through the inlet 20 and is metered by means of the valves
30 and 32 until a pressure of approximately 20 nt/m.sup.2 is
achieved within the reactor. A plasma is then struck by applying
the RF power between the electrodes 14 and 16 at a power of 100
watts. This plasma is generated for a period between 200 to 1,000
seconds or more. The purpose of the post plasma treatment is to
cross-link and stress-relieve the polymer films by ultraviolet
radiation, temperature elevation and electron bombardment. Although
argon is preferred, oxygen, air, nitrogen, and other noble gases
such as helium are also possible.
After the bombardment by the third plasma, the system is evacuated
to less than 0.67 nt/m.sup.2 and the vacuum is broken to room
atmosphere so that the substrate may be removed. During all of the
plasma generation stages, the flow rate is in the range of 1 to 5
cc/min. at STP (air). The throttling valve 30 utilized in the
experiments yielding the above data was a Nupro SS-12VAN, two and
one-half turns lock to lock right angle bellows valve. During the
pretreatment of the substrate by the hydroxyl group forming plasma,
the throttle valve 30 is typically one-quarter turn open, one-half
turn open during the post treatment with third plasma. The flow
valve 32 is utilized in the generation of the above data was a
Granville-Phillips series 203 manually operated variable leak
valve. The setting on the flow valve 32 during the pretreatment
with hydroxyl group forming plasma was typically 90, 92 during
deposition, and 78 during the post treatment with the third plasma.
These settings could vary by a plus or minus 5 depending upon the
variation in the ambient atmospheric conditions.
The invention is further illustrated by the following non-limiting
examples:
EXAMPLE I
The grounded lower electrode 16 was electrically isolated from the
metal support plate 18 to prevent current from flowing through the
lower electrode and the support plate. The support plate 18 was in
turn isolated from the metal base plate of the vacuum system, which
was further isolated from the ground. All gas flow lines (monomer
inlet, vacuum pump and pressure gauge) were joined with lengths of
glass tubing to prevent possible grounding through the
instrumentation of the pumping system.
This spacing between the electrodes 14 and 16 was kept at 5.0 cm
and the area of each electrode was 182 cm.sup.2. The samples to be
coated were located midway between the electrodes and were
supported by an aluminum table with Teflon.RTM. legs. The table
rested on the lower electrode 16.
The voltage applied to the upper electrode 14 was measured with a
Tektronix P 601 3A voltage probe; the current-to-ground was
measured with a Tektronix P 6021 current probe. Forward and
reflected power were read from the wattmeter incorporated into the
13.56 MHz RF power supply 26.
A PMMA substrate was masked with a glass cover slip, then subjected
to H.sub.2 O vapor plasma and then coated with a monomer mixture of
50% hexamethyldisilizane/50% vinyldimethylethoxysilane to a
thickness of 550 nm. The sample was then argon post treated as
described above.
The sample passed the tape pull adhesion test. A standard MIL spec
rubber eraser was used under a force loading of 2.25 lbs./in..sup.2
and abraded for 20 rubs. The "step" thereby produced was then
photographed under a light microscope of 40 power magnification
with dark field illumination. After the abrasion test, the sample
was cleaned with a standard lens cleaning solution and lens paper.
Subsequent inspection evidenced the increased durability of the
coated surfaces. The only scratches which did go into the coated
surface were due to small "hot spots" of pumice in the eraser which
caused force loading to increase by orders of magnitude because the
force applied to the eraser was transferred through a point contact
to the coating rather than being distributed over the whole surface
of the pad.
Coatings produced by the foregoing described method have shown a
high resistance to attack by water, Freon.RTM. and standard lens
cleaning solutions. Also, the coatings show no evidence of
delamination, discoloration or cracking when stored at temperatures
of 170.degree. F. (76.67.degree. C.) for 168 hours.
EXAMPLE II
A number of monomers were coated on various substrates according to
the procedure outlined in Example I. The coatings of Table I were
applied without the use of any hydroxyl group forming plasma or
post treatment plasma.
In Table II, substrates were pretreated with the hydroxyl group
forming plasma but not with the post treatment plasma.
In Table III, substrates were coated according to the present
invention, i.e., both plasma treatment steps were carried out. When
argon was used, a most superior coating was achieved.
TABLE I
__________________________________________________________________________
MONOMER PRESSURE POWER DURATION THICKNESS SUBSTRATE REMARKS
__________________________________________________________________________
Vinyltrimethylsilane 30-100.mu. 15-60W 1200- 1000- Glass Powder
formed. No adhe- 1500sec. 1600A PMMA sion. Poor durability.
Tetramethylsilane 50.mu. 30W 1200sec. 0 Glass No deposition. Would
50-70.mu. 15-100W PMMA not polymerize. Vinyldimethylethoxysilane
60-100.mu. 30-100W 1200- 1000- Glass Sporatic adhesion. Good
3000sec. 6000A PMMA durability. High deposi- tion rate.
Dimethyldiethoxysilane 35-70.mu. 30W 1200sec. 0 Glass No
polymerization. No deposition. Hexamethyldisilizane 30-100.mu.
30-100W 1200sec. 0- Glass Very low deposition 500A PMMA rate.
Tenacious adhesion. Poor durability. 50% (vol.)
Hexamethyldisilizane 72.mu. 60-100W 1200- 0 Very low deposition
rate 50% (vol) Vinyltrimethoxysilane 1400sec. PMMA No adhesion.
Poor durability. 50% (vol.) Hexamethyldisilizane 50-200.mu. 60W
1200sec. 1000- Large amounts of powder 50% (vol.)
Vinyltrimethylsilane 1300A PMMA found. 50% (vol.)
Hexamethyldisilizane 50-135.mu. 30-100W 1200sec. 400- Poor
adhesion. Sporatic 50% (vol.) Vinyldimethoxysilane 1000A PMMA
durability. Low deposi- tion rate. Vinyltrimethoxysilane 50-200.mu.
30-100W 1200- 1000A- PMMA Sporatic adhesion. 2000sec. 2microns
LEXAN Sporatic durability. Hexamethyldisiloxane 50-70.mu. 15-100W
2000- 4000- Poor abrasion resistance, 3000sec. 6000A LEXAN
Excessive powder forma- tion. Moderate
__________________________________________________________________________
adhesion.
TABLE II
__________________________________________________________________________
GAS PRESSURE POWER DURATION SUBSTRATE REMARKS
__________________________________________________________________________
Oxygen 100- 30- 100- Improved VTMS film but too 200.mu. 75W 300sec.
PMMA reactive due to sputtering polymer. Helium 250.mu. 75W 100-
Sporatic improvement in 300sec. PMMA durability and adhesion.
Majority fail adhesion test. Air 100.mu. 75 150sec. PMMA Sporadic
improvement. Films partially fail adhesion test. H.sub.2 O 50- 30-
100- PMMA Films show good adhesion. 115.mu. 60W 400sec. LEXAN
Styrene Polymer
__________________________________________________________________________
TABLE III
__________________________________________________________________________
GAS PRESSURE POWER DURATION SUBSTRATE REMARKS
__________________________________________________________________________
Argon 70-150.mu. 60-100W 100-900 PMMA Improved abrasion sec. LEXAN
resistance without film Styrene sputtering. Polymer Helium 70.mu.
20W 100- Poor adhesion. Poor 15000sec. PMMA durability
__________________________________________________________________________
* * * * *